28 lines
883 B
Rust
28 lines
883 B
Rust
// Copyright 2015, 2016 Ethcore (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Common math functions.
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/// Returns log2.
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pub fn log2(x: usize) -> u32 {
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if x <= 1 {
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return 0;
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}
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let n = x.leading_zeros();
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::std::mem::size_of::<usize>() as u32 * 8 - n
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}
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